The present invention relates to the medical diagnostic and surgical arts. It finds particular application in conjunction with stereotactic surgery and will be described with particular reference thereto. However, it is to be appreciated that the invention will also find application in conjunction with minimally invasive surgery, neurosurgery, neurobiopsy, CT-table needle body biopsy, breast biopsy, endoscopic procedures, orthopedic surgery, other invasive medical procedures, industrial quality control procedures, and the like.
Three-dimensional diagnostic image data of the brain, spinal cord, and other body portions are produced by CT scanners, magnetic resonance imagers, and other medical diagnostic equipment. These imaging modalities typically provide structural detail with a resolution of one millimeter or better. Various frameless stereotaxy procedures have been developed which take advantage of three-dimensional image data of the patient. These procedures include guided-needle biopsies, shunt placements, craniotomies for lesion or tumor resection, and the like. Another area of frameless stereotaxy procedure which requires extreme accuracy is spinal surgery including screw fixation, fracture decompression, and spinal tumor removal.
In brain biopsy procedures, for example, surgeons or other medical personnel drill and tap a hole in a patient's skull. Surgeons have come to rely on frameless stereotaxy procedures for placing and orienting the bit of the surgical drill prior to forming the hole in the skull. These procedures require aligning images of fiducials or markers, affixed at three or more spaced points on the patient's body, with known fiducial positions in patient space. The fiducials are spherical markers or small beads that are injected with radiation opaque and magnetic resonance excitable materials and fit within a fiducial positioning cup. Therefore, the fiducials are visible in the imaging medium selected such that they show up as readily identifiable dots in the resultant image data.
Heretofore, the fiducials have been affixed directly to the patient's body using a glue. Fiducials have also been attached to a patient's skull using screws. However, these methods of attachment have proven undesirable, especially if it is necessary to remove,the fiducials for a period of time before they are reattached. Because the imaging modalities discussed above typically provide structural detail with a resolution of a millimeter or better, it is critical that the fiducials be reattached as close as possible to the exact location where they were previously located. Such accuracy is difficult to achieve when using a glue to attach the small, spherical fiducials directly to the patient's body.
The present invention provides a new and improved apparatus and method which overcomes the above-referenced problems and others.